Fire-extinguisher.



W. L. HARRISON.

FIRE EXTINGUISHER.

ArvucAnoN mso Mlm. 2s. 1915.

Patented m1219156.

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WITNESS.-

time eras onion.

FIRE-EXTINGUISHER.

Specification of Letters Patent.

Patented Deel2, 191th.

Application led March 23, 17,915. Serial No. 16,327.

To all whom it may concern.'

Be it knownvthat I, WILLIAM L. HARRI- soN, a citizen of the UnitedStates, and resident of Branford, in the county of New Haven and Stateof Connecticut, have invented certain neuT and useful Improvements inFire-Extinguishers, of which the following is a specification.

My present invention relates to fire-eX- tinguishers of the type whichcomprises a container divided by a so-called floating piston into twocompartments one of which 1s filled withthe fire-extinguishing fluid,while the other compartment holds a charge of compressed gaseous mediumacting to eX- pel the said fluid as soon as the outlet is opened. Inapparatus of this class, difficulty is often experienced in obtaining aproper fit of the piston, and the object of my present invention is toovercome this drawback. For this purpose, l have devised the improvednovel construction described and claimed hereinafter, whereby 1 secureautomatically, a varying tightness of the joint between the piston andthe wall of the container, so that, as explained in detail hereinafter,the piston will be pressed against the container wall with greater orless force at different stages of the operation, just as required tosecure the best results.

Reference is to be had to the accompanying drawings, in which- Figure 1is a central longitudinal section through a fire-extinguisher embodyingmy improved piston constructiong. Fig. 2 isa cross section on line 2 20f Fig. 1; Figs. 8 and 4 are detail longitudinal sections, upon anenlarged scale, showing a portion of the piston and of the adjacentcontainer wall in two different conditions, to illustrate the working ofmy improved construction; and Figs. 5 and 6 are partial longitudinalsections of two other forms of my invention.

rl`he general features of the lire-extinguisher shown in these drawingsform no part of my present invention, and .will therefore bedescribedbut briefly.

A is the cylindrical container, divided into a compartment A adapted tohold the charge of extinguishing liquid (for instance, carbontetrachlorid), and another compa-rtment A, adapted to be filled withcom-` pressed air.

B is a suitable cock or valve controlling the outlet from thecompartment A and C is an air-valve, similar ,Lto those employed forpneumatic tires, and protected by caps D, D this valve serves for theadmission of compressed air to the compartment A.`

The two compartments A', A are separated by the AHoating piston E, towhich my invention relates more particularly. As shown in Figs.` '1 to 4this piston comprises two metal plates or washers E through whichextends loosely a central screw E receiving at one end a nut E*,.theother end of the screw having a .suitable head engaging one of thewashers E. Between the two washers is located the piston body E2 and thepiston cup or washer E3, made of leather or other suitable materialwhich will present a smooth surface for sliding engagement with theinner wall of the container A. The edge or flange of this leather washeris bent toward the air-compartment A. The piston body E2 consists ofappropriate soft elastic material, for which purpose I have found feltparticularly suitable. The washers E are of smaller diameter than thepiston body, so that, as shown, the marginal portion of the latter willproject beyond the said hard (metal) washers or plates. The piston bodyis preferably treated with glycerin by dipping it into a glycerin bath,.and the leather washer E3 also preferably receives a coating ofglycerin, atleast on its outer side. rlhis coating or impregnation ywithglycerin is employed'for the Vpurposes indicated in Letters ,Patent ofthe United States No. 1,106,144 issued to me on August 4, 1914; that isto say, the glycerin is employed partly as a lubricant for the piston,'and partly for the purpose of absorbing any moisture that may bepresent and of thus preventing the formation of hydrochloric acid orother injurious compound. rlhe nut E* projects below the piston properand is adapted to strike the projection A3 on the bottom A2 so as toprevent the piston proper .from coming in contact with the bottom of thecontainer when the piston is in its lowermost position; this nutpreferably hasa funnel-shaped guiding surface for the purpose lofcentering a rod which may be introduced through the projection A3, whenit is desired to push the piston back after the charge ofhre-extinguishing fluid has been expelled. The piston may also beconnected with a wire guard E4 of the same character as the one shown inmy above-mentioned patent, the purpose of said guard being to keep thepiston steady and also to prevent it from striking against the housingof the air valveC. v

It will be obvious that the pressure of the air in the compartment A andthe'equal counteracting pressure of the liquid in the compartment A, aregreatest when the piston is in the initial or highest position shown inFig. l, and will decrease as the piston moves toward the outlet cock B.rlhe pressure acting on opposite sides of the piston compresses the softelastic piston body E2 so as to reduce its thickness and to force itsmarginal portion toward the wall of the container. When the parts are inthe position shown in Figs. 1 and 3, the air pressure acting downwardlyand the pressure or resistance of the liquid acting `upwardly on thepiston, are greatest so that the marginal portion of the piston body E2will be pressed outward most forcibly. This will result in fiatteningthe marginal or peripheral portion of the piston body as shown best inFig. 3, so as to cause the cup or washer E3 to be brought in contactwith the wall of the container along a comparatively wide surface. AThusthe danger of the passage of air orv of carbon tetrachlorid from itsproper compartment tothe other compartment will be least at the timewhen pressure is greatest, since at that time the barrier formed by thepiston washer Ewill be most effective. When the cock B is opened and theliquid is discharged by the movement of the piston under the influenceof the compressed air, it will be obvious that the air pressuredecreases more and more as the piston approaches the outlet. The softelastic piston body E2 will therefore be subjected to a longitudinalcompression and radial eXpansion of gradually diminishing force, and asa result thereof the area of the surface on which the washer E3 is incontact with the wall of the container will become progressively less,reducing to la corresponding eX- tent-theamount of friction between thepiston and the wall of the container. Thus, as

the vpropelling force of the compressed air decreases, this iscompensated for by the reduction yin the friction between piston andcontainer. When the piston'is in its lower- Vmost position, the body E2and the washer E3 may be substantially in the relation illustrated inFig. 4c, in which the thickness of thepiston body is greater than inFig. 3 and in which the contact surface between piston washer vandcontainer wall is'much smaller thanin Fig. 3. When thefire-extinguishing fluid has been expelled fully, the air valve Cisopened toallow air to escape from the compartment r the piston is theneX- posed only to atmospheric pressure on both sides, and thecontactAsurface between the piston vwasher and the container wall will I be'reduced to a minimum.` It therefore Ywill be easy to push the pistonback preparatory to refilling the compartment A wifh thefire-extinguishing liquid.

In the form of my invention illustrated by Fig. 5, the piston washer orcup E3 is dispensed with, and the container wall is engaged directly bythe marginal portion of the piston body E5, which might consist asbefore of felt treated with glycerin, or such body might be made of acomposition containing gelatin, glycerin and graphite, or in general anysoft elastic material. In Fig. G, the piston body E5 is used inconjunction with two disks or layers of felt F which, if desired, may betreated with glycerin. In each of these two cases, I have also shown themetal plates E and the screw E for holding the parts of the pistontogether. It will be understood-that the operation of the forms of myinvention shown in Figs. 5 and 6 is the same as explained above withreference to Figs. 1 to 4 inclusive.

Various modifications may be made without departing from the nature ofmy invention as defined in the appended claims.

I claim:

l. The combination of a container having an outlet, a manuallyoperatable valve controlling said outlet, .and a piston movable in saidcontainer and dividingit into two compartments adapted to be filledrespectively with a compressed gaseous medium and with liquid, saidpiston being made of soft elastic material and engaging the wall of thecontainer with progressively diminishing force as the pressure of saidgaseous medium decreases during the movement of the piston toward saidOutlet.

2. The combination of a container having an outlet, .a manuallyoperatable valve controlling said outlet, and a piston movable in saidcontainer and dividing it into two compartments adapted to be filledrespectively with a compressed gaseous medium and with a liquid, saidpiston being deformable in response to variations of pressure within thecontainer in such a manner as to reduce the friction between piston andcontainer wall when the pressure decreases.

3. The combination of a container having an outlet, a manuallyoperatable valve controlling said outlet, and a piston movable in saidcontainer and dividing it into two compartments adapted to be filledrespectively with a compressed gaseous medium and witha liquid, saidpiston being compressible axially and expansible radially in response toan increase of pressure within the container.

4. The combination of a container having an outlet, a manuallyoperatable valve controlling said outlet, and a piston movable in saidcontainer and dividing it into two compartments adapted to be filledrespectively with a compressed gaseous medium and with a liquid, saidpiston comprising a holding' device having; two connected abutnients,rigid washers mounted loosely between said abutments so as to be capableof moving' toward and from the saine, and a piston proper locatedbetween said washers, said piston proper being1 compressible axially andoxpansible radially in response to an increase of pressure within thecontainer. The combination of a container having an outlet, av manuallyoperatable valve controlling said outlet, and a piston movable in saidcontainer and dividing' it into two compartments adapted to be filledrespectively with a compressed gaseous medium and with a liquid, saidpiston comprising .a bodv of soft elastic material and a cupshapedwasher of smooth-surfaced material having its iiange litted around theedge of the piston body and in engagement with the container Wall.

ln testimony whereof I have signed this specication, in the presence oftwo subscribing' witnesses.

WILLlAM L. HARRlSQN.

Witnesses WILLIAM J. MGENTEE, EDITH M. NICHOLSON.

Copies of 'this patent may be obtained for five cents each, byaddressing the Commissioner of Patents. Washington, D. C.

